the 7005 alloys allow for a lighter frameset, simply because you need less material for the same strength as 6082 or similiar 6XXX alloys: you can use a thinner wall or smaller tube, which also changes the ride feel
i worked extensively in 6082 (HE30) in the UK making prototype frames, which always ended up heavier than the 7005 frames my factory in Australia was making my production frames from. we could not source 7XXX tubes in the UK otherwise i would have jumped on them..
A big problem with 6082 was the expensive, time consuming and temperature critical T6 heat treatment; compared to 7005 frames which would harden in their packaging whilst 'on the boat' following post weld alignment
I used to sell a lot of USA made Zaskars whilst working at one of the UK's leading GT dealers and we had a large number back cracked due to poor QC during heat treatment